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  3. Reuse DC solution from a specific corner in one test in...

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Reuse DC solution from a specific corner in one test in the same corner of a different test

Analog Pete
Analog Pete over 1 year ago

There are two independent loops in my circuit that I want to run stability analysis for.  Since a Maestro Test can have only one analysis of a given type, I have two Tests.  The only difference between the two tests is the terminal I specify for "Probe Terminal" in the stb analysis configuration.  I am running over corners and the DC solution can take a while to converge.

Is it possible to use the DC solution from my Loop1 Test in my Loop2 test?  Somehow I have to match the DC solution between the two Tests corner-to-corner.  I don't know how to do that.

Assembler/Explorer from Virtuoso version IC6.1.8-64b.500.32

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  • DomiHammerfall
    DomiHammerfall over 1 year ago

    I think the prevoppoint option works also across different tests. in your stb analysis form, click on the Options button at the very bottom and select the prevoppoint checkbox. The stb analysis will then use the last saved operating point, i.e. the OP of the previous analysis (the order matters!). 

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  • Analog Pete
    Analog Pete over 1 year ago in reply to DomiHammerfall

    Thank you for the reply.  Would prevoppoint correctly deal with the corner-to-corner match?  I guess I can try and see what happens...

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  • DomiHammerfall
    DomiHammerfall over 1 year ago in reply to Analog Pete

    My understanding is that prevoppoint just uses the very last simulation run that stored a DC operating point of the circuit, regardless from where it comes. So no, you will not have a corner-to-corner match unless you run them one by one, i.e. the order has to be:
    1. Corner A, Test1
    2. Corner A, Test2
    3. Corner B, Test1
    4. Corner B, Test2
    5. Corner C, Test1
    6. Corner C, Test2

    ADE Assembler has this feature called Run Plan. Maybe you can achieve the desired behaviour that way.

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  • Analog Pete
    Analog Pete over 1 year ago in reply to DomiHammerfall

    I have successfully used Run Plans, for example, in a Monte Carlo context, where I want to "factory trim" an MC trial and use a calculated trim code in subsequent Tests at different temperatures and supply voltages.  In that case, calcVal provides the necessary link.  It allows the Test, Run, and Corner each to be specified.  I need something similar to this calcVal functionality that can grab a specific DC solution.

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  • Analog Pete
    Analog Pete over 1 year ago

    A colleague just pointed me to this community post:
    https://community.cadence.com/cadence_technology_forums/f/custom-ic-design/47058/consistent-path-to-results-for-corner-simulation

    Something like this might work.

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  • Andrew Beckett
    Andrew Beckett over 1 year ago in reply to Analog Pete

    Use of prevoppoint will not work across corners or different tests. It's solely useful for a second analysis within the same invocation of Spectre.

    The approach I suggested in the post you linked to will do what you want.

    Andrew

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  • Analog Pete
    Analog Pete over 1 year ago in reply to Andrew Beckett

    Thank you, Andrew

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